Covers are applied to surfaces for reasons which depend on the nature of these surfaces. Thus, in the case of a pond such as a swimming pool, the cover can avoid pollution by leaves or animals and provide savings on energy, water and reagents, and can or must ensure safety of people, in particular of children. In a desalination pond or other fluid treatment pond, a cover makes it possible to avoid the liquid dilution due to rain or excessive evaporation due to heat.
In the case of a sports field such as a clay or grass outdoor tennis court, a cover makes it possible to protect it against bad weather, in particular intermittent rain. Moreover, a vehicle body is notably covered to ensure the stability of the load with respect to the dip in pressure caused by the movement of the vehicle and protect it against bad weather. Covers are also used as blinds for greenhouses, winter gardens or vehicle windows in order to avoid any internal overheating, and as solar protection for terrace awnings.
In all cases, the aim is generally to obtain an economical cover device that allows for easy, safe, reproducible and rapid covering and uncovering, requiring minimal human intervention and, above all, that has a life that is as long as possible. Numerous devices for covering a surface have been developed, ranging from the basic to the most sophisticated models. For example, a totally basic first device used in the case of a swimming pool comprises an inflatable or non-inflatable cover that is unwound, extended and fixed manually on the edges of the swimming pool. This type of device is illustrated for example in the documents U.S. Pat. No. 6,691,334, GB2379163 and FR2652373. Clearly, here, given the handling and the storage it relates only to swimming pools of fairly small size.
For surfaces of larger dimensions, cover devices can be used that also have a drum fixed at one of the transverse ends of the surface to be protected. The cover is deployed manually by pulling force, by unwinding from the drum, to cover the surface. The weight and the dimensions of the cover require the involvement of several people in order for it to be put in place appropriately. The cover is removed by winding it around the drum by rotation: the cover is then removed from the surface by sliding it over the latter. The rotation of the drum to remove the cover is produced manually or by means of an electric motor that has sufficient power to pull the fully deployed cover. It must be stressed that easy deployment of the cover, particularly in the case of a swimming pool, contributes to its safety, because labored handling would hamper its use. The deployment (that is to say its unwinding from the drum) and the removal (that is to say its rewinding onto the drum) of the cover can be done manually or automatically using a motor. Automatic cover devices are illustrated notably in the following documents: U.S. Pat. No. 3,574,979, GB2199741, US2005/0097834, CA2115113, US2001/0023506, U.S. Pat. No. 5,930,848, U.S. Pat. No. 4,001,900 However, this type of cover device with fixed drum described above has the major drawback of making the cover, which is dragged over the surface to be protected upon its deployment and its removal, slide, which generates premature wear thereof and greater work due to the duly generated frictions.
In the present application, the terms “longitudinal”, “transverse”, and their derivatives, refer respectively to the direction of movement of the drum and to the direction of the axis of revolution thereof.
In order to mitigate the drawback of the devices with fixed drum, a novel type of cover device with drum has been developed, in which the motorized drum is mounted on a longitudinal translation mechanism. The latter moves the drum over the surface to be covered which literally makes it possible to “lay” the cover on the surface, upon its deployment, by unwinding it simultaneously from the drum during its longitudinal movement, then lift it, upon its removal, by winding it simultaneously onto the drum. The cover therefore does not slip over the surface either upon its deployment or upon its removal. The cover device also comprises a system for fixing the cover at a transverse end of the surface to be covered such that the translation and the rotation of the drum result in the unwinding or the winding of the cover over the surface to be covered. Examples of automatic devices of this type are disclosed, for example, in the following documents: WO2005/026473, FR2900951, DE2257231, FR2893651, FR2789425, FR2743502, EP1719858, Moreover, a completely manual variant of the drum mounted with longitudinal translation is illustrated in the documents WO2007/036625 and U.S. Pat. No. 4,195,370.
The moving drum cover devices illustrated above provide only a fixing of a transverse edge of the cover at a transverse end of the surface to be covered, the opposite edge remaining secured to the drum. No system for fixing the longitudinal edges of the cover is provided. In particular, in the case of a swimming pool, people moving onto the cover would not be retained by its longitudinal edges and could thus be plunged into the water. Furthermore, the lack of sealing of the cover on its longitudinal edges can promote the ingress into the swimming pool of dirt, dead leaves and twigs, as well as small animals such as mice or snakes. More sophisticated devices have been proposed that make it possible to reversibly fix the longitudinal edges of the cover upon its deployment, as in the document FR2803769 which provides a system for fixing the longitudinal edges of the cover consisting of grid sections that are raised then folded back section by section on said longitudinal edges of the cover by keeping these edges inside a gutter as the latter is unwound. In this design, the longitudinal edges of the cover are gripped without being locked, which provides lesser security, particularly in the case of swimming pools.
Another advantageous system that makes it possible simultaneously to fix the longitudinal edges of the cover upon its deployment and exert a transverse pulling force thereon to tighten it perfectly has been disclosed in WO2010/010152 and in WO2010/054960. In these devices, the longitudinal edges of the cover are provided with a cord or bead which is introduced into the upwardly oriented opening of a rail in the form of a “U” section profile member, with one or two fins partially closing said opening. The bead which slips under a fin and is retained in this position by suitable fixing means, makes it possible to securely fix the longitudinal edges of the cover.
Such a cord, or bead, advantageously consists of a braid forming the core of the bead, jacketed in a fabric, generally woven or braided, the free edges of which are fixed onto at least one of the two faces of the cover along its longitudinal edges with a glue, by spot welding or, more advantageously, by stitching. An example of such a bead is represented in FIG. 2. US2003/0097709 describes a cord of this kind, in which a bead is formed by a substantially cylindrical core jacketed in a fabric strip, the free edges of which are fixed to a cover comprising a vinyl coating by hot air welding. The welding is performed using hot air guns oriented toward the interface of the free strips of the jacketing fabric and the two surfaces of the cover directly downstream of two pressure rollers applying a pressure onto the duly heated strips and covers. In FIG. 13 of US20130097709, it can be clearly seen that the weld extends exclusively to the free strips of the jacketing fabric while the core and the part of the fabric in direct contact with the core are not targeted by the air guns and are not compressed by the pressure rollers.
This solution is satisfactory, but, after a certain period of use, a puckering of the longitudinal edges of the cover is observed, which has the drawback of giving more volume to the cover wound on the drum and, above all, the major drawback of preventing the correct engagement of the bead in the opening of the rail.
The present invention proposes a form of bead extending along the longitudinal edges of the cover of a device with moving drum, which has better mechanical stability over time than the solutions hitherto proposed.